2010-04-26_PERMIT FILE - C1980007A ‎(3)‎

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 4/26/2010
• Doc Name: Refuse Pile Expansion East
• Section_Exhibit Name: Exhibit 82 Refuse Pile Expansion East
• Media Type: D
• Archive: Yes

4.0 RPE East Refuse Pile Permit Design
The RPE East refuse pile design is presented on the permit drawings provided in Appendix D. The
layout of the refuse pile is based on geotechnical analysis and design provided in Section 2. Key
components of the refuse pile design are presented below. RPE East refuse storage capacity is shown
in Appendix G.
4.1 Stripping
Prior to placement of coal refuse in the RPE East refuse pile, the area being prepared for refuse
placement will be stripped of soils and colluvium down to bedrock. The colluvium will be placed in
horizontal windrows orientated generally perpendicular to the face of the refuse pile within the refuse
material to minimize interference with refuse pile drainage and to minimize potential for negative
impact to geotechnical stability. Where beneficial to the stability of the refuse pile, colluvium will
be mixed with wet refuse fines to absorb moisture. The extent of such areas will be kept to a
minimum to avoid developing low- permeability zones within the refuse pile. Vegetative soil stripped
from the refuse pile foundation zone will be used for contemporaneous reclamation as the face of the
refuse pile reaches design grade (Rule 4.13).
4.2 Buttress
A rock buttress will be constructed at the toe of the RPE East refuse pile to increase stability of the
refuse pile as required by Rule 4.09.1(10). Prior to buttress construction, the buttress area will be
stripped of soils and colluvium down to bedrock. A keyway cut will be placed at the toe of the
buttress to enhance stability. The buttress will consist of rock with colluvium on the upstream face
only, excavated from the initial refuse pile development area. The buttress will have a 1.5H: IV
slopes on its north face (away from the refuse pile) and a 1H: IV slope on the south face where refuse
will be placed.
4.3 Drainage Blanket
A drainage blanket will be provided by ripping in -place sandstone to a depth of approximately one
foot to create a set of trenches that lie approximately perpendicular to the contours of the refuse pile
foundation, or by placing sandstone excavated to a thickness of approximately one foot, beneath the
refuse pile to direct subsurface drainage to the underdrain. This drainage blanket will be on the
bedrock surface under the refuse pile after it has been stripped of soils and colluvium. HELP model
0 results indicate that the drainage blanket will be adequate to prevent head build up below the refuse.
PAMpls \06 CO \26 \06261003 MCC Refuse Pile Site Review & Permit \WorkFiles\Permit Application \Text \2010- 04- 19_RPE East Permit Application. doc14.